• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.1A
• /
• pp.45-52
• /
• 2009

In conventional structural design, deterministic optimization which satisfies codified constraints is performed to ensure safety and maximize economical efficiency. However, uncertainties are inevitable due to the stochastic nature of structural materials and applied loads. Thus, deterministic optimization without considering these uncertainties could lead to unreliable design. Recently, there has been much research in reliability-based design optimization (RBDO) taking into consideration both the reliability and optimization. RBDO involves the evaluation of probabilistic constraint that can be estimated using the RIA (Reliability Index Approach) and the PMA(Performance Measure Approach). It is generally known that PMA is more stable and efficient than RIA. Despite the significant advancement in PMA, RBDO still requires large computation time for large-scale applications. In this paper, A new reliability-based design optimization (RBDO) method is presented to achieve the more stable and efficient algorithm. The idea of the new method is to integrate a response surface method (RSM) with PMA. For the approximation of a limit state equation, the moving least squares (MLS) method is used. Through a mathematical example and ten-bar truss problem, the proposed method shows better convergence and efficiency than other approaches.

• Applied Chemistry for Engineering
• /
• v.27 no.4
• /
• pp.433-438
• /
• 2016

The current study evaluated the air quality of the smoking booth equipped with the air purification system consisting of photocatalysts and air filters by measuring the concentrations of hazardous substances of tobacco smoke such as CO, HCHO, $CH_3CHO$, PM10 and PM2.5. To enhance the removal efficiency of hazardous substances, an infrared ray was exposed to improve the reactivity of OH radical generated from the photocatalyst toward environmental tobacco smoke (ETS) gas phase hazardous materials. It was found that the smoking booth with the air purification system improved the removal efficiency of hazardous substances containing formaldehyde by 85.2% compared to that of the smoking booth without any purification systems. In addition, the removal efficiency of the fine dust after treatment was enhanced up to 89.4%.

• The Journal of the Korea Contents Association
• /
• v.9 no.5
• /
• pp.174-181
• /
• 2009

Recently hospitals are implementing a One Stop Service as part of patient-care service. With the One Stop Service, medical treatment including consultation, inspection, and results are changing to be made available in one visit. Therefore most examinations are reserved for the same day; however, there are cases in which additional visits are necessary because of certain properties related to exams. This study compares and analyzes the number of reinspections before and after reforms. By designating the order of priority for BMD examinations and implementing education from information obtained in the OCS E-manual update, the number of reinspections for wards was reduced from 58 to 21, Outpatient departments were reduced from 51 to 12, and errors in reservations made by employees in the department of radiology were reduced from 98 to 11. Reinspections can be reduced with full understanding the factors related to reinspection and a background check prior to inspection in order to determine the order of priority for inspections. This will also reduce workers' stress and increase their efficiency and at the same time decease patient dissatisfaction and improve hospital reliability.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.4
• /
• pp.401-407
• /
• 2011

The conventional method of magnetic abrasive polishing is not suitable for non-magnetic materials because such polishing is basically possible when magnetic force exists and the magnetic force in non-magnetic materials is very low. The installation of an electromagnet under the working area of a non-magnetic material, which is called second-generation magnetic abrasive polishing in this study, can enhance the magnetic force. Experimental evaluation and optimization of process parameters for polishing magnesium alloy steel was performed by adopting the design of experiments and the response surface method. The results indicated that the intensity of the magnetic force and spindle speed are significant parameters that affect the improvement of surface roughness. A prediction model for the surface roughness of the magnesium alloy steel is developed using the second-order response surface method.

• Journal of Digital Convergence
• /
• v.10 no.11
• /
• pp.395-402
• /
• 2012

This study has been conducted to design and implement smart phone-based application which can keep records effectively to improve athletes' ability. To boost their performance, they need to receive training as realistic as possible. As a way to do that, training should be performed with some fitness equipments, sporting apparatus, facilities, and conditions. However, it is also possible to improve their ability by motivating athletes with checking and recording their performance. This study ascertains that using scoring records actually motivates athletes when comparing the result of youth basketball team using the records keeping system with that of not using it. Accordingly, smart phone-based records keeping application has been designed and developed. Also, through a survey targeting athletic coaches who have used the system, training efficiency has been measured and it turns out that it actually motivates athletes to improve their abilities.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.7
• /
• pp.9-14
• /
• 2003

In this work, a multi-block/multi-partitioning method is suggested for a multi-block parallelization. It has an advantage of uniform load balance via subdividing of each block on each processor. To make a comparison of parallel efficiency according to domain decomposition method, a multi-block/single-partitioning and a multi-block/ multi-partitioning methods are applied to the flow analysis solver. The multi-block/ multi-partitioning method has more satisfactory parallel efficiency because of optimized load balancing. Finally, it has applied to the CFDS code. As a result, the computing speed with sixteen processors is over twelve times faster than that of sequential solver.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.309.2-309.2
• /
• 2013

Cu(In,Ga)Se2 (CIGS) 박막 태양전지는 일반적으로 Na을 함유하고 있는 소다회유리를 기판으로 사용하여 제작되며, 높은 광전 변환 효율로 인해 많은 연구가 이루어지고 있다. 특히 제조 비용 절감과 양산성 향상을 위해 현재 유연 기판 CIGS 박막 태양전지에 대한 연구가 활발히 이루어지고 있으며, 폴리이미드 기판에서 20.4%의 최고 효율이 보고되었다. 유연 기판은 유리 기판 대비 무게가 가볍기 때문에 유리 기판 태양전지보다 활용도가 높으며, 우주용으로 사용할 경우 단위 무게 당 발생되는 전력이 높은 장점이 있다. 본 연구에서는 폴리이미드 기판을 이용하여 유연 CIGS 박막 태양전지를 제작하였다. 후면 전극 Mo은 DC sputtering으로 증착하였으며, Mo의 증착 압력에 따라 폴리이미드 기판의 잔류 응력과 전기적 특성을 분석하여 증착 압력을 결정하였다. 광흡수층인 CIGS는 다단계 동시 증발 법으로 증착하였으며, 2nd stage 공정온도는 유리 기판 대비 저온인 $475^{\circ}C$로 공정을 진행하였다. 저온공정인 $475^{\circ}C$ 공정에서는 Ga의 함량이 높아질수록 성능이 감소하였으며, Na 공급을 통해 Voc와 FF가 향상되어 성능이 향상됨을 알 수 있었다. 버퍼층 CdS는 습식 공정인 CBD법으로 증착하였으며, 공정변수인 thiourea의 농도와 CdS 박막의 두께 변화를 통해 폴리이미드 기판 CIGS 박막 태양전지에서 CdS 버퍼층의 최적의 조건을 도출하였다. 최종적으로 제작된 폴리이미드 기판 유연 CIGS 박막 태양전지는 반사 방지막 없이 개방전압 0.511V, 단락전류밀도 32.31mA/cm2, 충실도 64.50%, 변환효율 10.65%를 나타내었다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.4
• /
• pp.840-845
• /
• 2007

In a wireless sensor network, a middleware used to support efficient processing and fast delivering of sensing data should handle the data loss problem at an intermediate sensor node caused by unexpected sudden data burst. In his paper, it proposes a Delta-Average method for enhancing the efficiency of data aggregation and correctness where the sensed data should be delivered only with the limited computing power and energy resource. With the proposed method, unnecessary data transfer of the duplicate data is eliminated and data correctness is enhanced by using the proposed averaging and data differentiating scheme when an instantaneous data burst is occurred. Finally, with the TOSSTM simulation results on TinyDB, we verify that the correctness of the transferred data is enhanced.

• Journal of the Korea Convergence Society
• /
• v.10 no.6
• /
• pp.41-47
• /
• 2019

It is very important to search for and obtain an example of a similar judgment in case of court judgment. The existing judge's document search uses a method of searching through key-words entered by the user. However, if it is necessary to input an accurate keyword and the keyword is unknown, it is impossible to search for the necessary document. In addition, the detected document may have different contents. In this paper, we want to improve the effectiveness of the method of vectorizing a document into a three-dimensional space, calculating cosine similarity, and searching close documents in order to search an accurate judge's example. Therefore, after analyzing the similarity of words used in the judge's example, a method is provided for extracting the mode and inserting it into the text of the text, thereby providing a method for improving the cosine similarity of the document to be retrieved. It is hoped that users will be able to provide a fast, accurate search trying to find an example of a tax-related judge through the proposed model.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10b
• /
• pp.472-474
• /
• 2004

본 연구는 레거시 시스템의 인터페이스 정보로부터 의미 있는 정보를 파악하여 새로운 시스템에 통합될 수 있도록 하기 위한 기존 레거시 시스템의 인터페이스에 기반한 객체추출 기법을 제안한다. 본 논문에서 제안하는 객체추출 기법은 인터레이스 사용사례 분석 단계, 인터페이스 객체 분할 단계, 객체구조 모델링 단계, 객체 모델 통합 단계 등 4단계로 구성되어 있다. 인터페이스 사용사례 분석 단계는 인터페이스 구조, 레거시 시스템과 사용자간의 상호작용 정보를 획득하는 단계이다. 인터페이스 객체분할 단계는 인터페이스 정보를 의미 있는 필드들로 구분하는 단계이며, 객체구조 모델링 단계는 인터페이스 객체들간의 구조적 관계와 협력 관계를 파악하여 모델링 하는 단계이다. 마지막으로 객체 모델 통합 단계는 객체 단위의 단위 모델들을 통합하여 추상화된 정보를 포함한 상위 수준의 통합 모델을 유도하는 단계다. 객체추출 기법에 의해 생성된 객체 통합 모델은 역공학 기술자들의 레거시 시스템 이해와 레거시 시스템의 정보를 새로운 시스템에 적용하는데 있어 효율성을 극대화할 수 있다.